You shouldn't need to replace the calipers or master cylinder. A simple rebuild on both, replaceing the brake lines, and doing a proper job of bleeding the system out will make them work just fine.

If you are 100% sure you bleed the system and there is no air in the system then I would look at rebuilding the calipers, and then the master cylinder.

of course if either of those were to be at fault, you would see them leaking. If they are not leaking then it's your bleeding the system that didn't work. Get a Mighty Vac (power bleeder) and you should be good. If your hoses are crap, replacing them will also help.
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Charles Gallant